EPA biofuels rule: calculating the payback

The EPA released a report yesterday that proposes to change the rules of the biofuels game. The report, titled “Regulation of Fuels and Fuel Additives: Changes to Renewable Fuel Standard Program,” examines the lifecycle of corn-for-ethanol practices and sets the “payback” period of carbon emissions for corn-for-ethanol fuel as 33 years.

The payback period means that at first, corn-for-ethanol practices will be a net source of carbon into the atmosphere, as clearing farmland using fire and releasing carbon from soil create initial bursts of carbon release. Over time, however, the system will become self-sustaining and will become a net sink for carbon.

Although environmentalists, including the National Resource Defense Council, have spoken up in favor of the EPA’s rule, the biofuels mandate still leaves a lot of wiggle room for revelation of corn ethanol’s true nature, especially under required production.

For example, as posed by the Roger Pielke on the Prometheus blog, a question that remains is how long it will take to develop an even better biofuel standard than the current corn practices, which are not efficient. If this development time is less than 33 years, but the law mandates commitment to corn as a fuel source for at least 33 years, then the law will in effect create a net source of carbon. As he puts it:

“Does it make sense to incur very large increases in carbon dioxide emissions in the short-term under a promise of benefits to occur many decades into the future?”

EDIT: For a simple breakdown of the EPA’s scenarios and an interview with Tim Searchinger, a scientist who allegedly published the first paper showing that corn ethanol production increases greenhouse gas emissions, check out this Grist article.